The present invention relates to the use of particular strains of feline caliciviruses for the production of immunogenic preparations and of vaccines, in particular inactivated or subunit vaccines, against feline calicivirosis. These immunogenic preparations and these vaccines may also be combined with immunogenic preparations or vaccines prepared on the basis of other feline pathogens, for the production of multivalent immunogenic preparations and vaccines.
Feline caliciviruses (FCV) were first described in 1957 (Fastier L. B. Am. J. Vet. Res. 1957. 18, 382-389). Feline caliciviruses are, with the feline herpesviruses, the two principal sources of viral diseases of the upper respiratory tract in cats. The FCV viruses affect a large number of animals, with FCV carrying rates of the order of 15 to 25%, and an anti-FCV seroprevalence of 70 to 100% (Coutts et al. Vet. Rec. 1994. 135. 555-556; Ellis T. M. Australian Vet. J. 1981. 57. 115-118; Harbour et al. Vet. Rec. 1991. 128. 77-80; Reubel et al. Feline Dendistry 1992. 22. 1347-1360). After an initial phase of hyperthermia, these respiratory diseases are generally accompanied by buccal ulcerations (palate, tongue, lips, nose), rhinitis, conjunctivitis, possibly anorexia and asthenia. The FCV viruses can also cause pneumonia, enteritis, and articular pain (lameness syndrome).
The FCV virus is transmitted only horizontally, there is no vertical transmission from the mother to its kitten during gestation (Johnson R. P. Res. Vet. Sci. 1984. 31. 114-119). FCV is transmitted by contact between infected animals and healthy animals or by the airways during sneezing (Wardley R C. Arch. Virol. 1976. 52. 243-249).
Feline caliciviruses are naked viruses of the Caliciviridae family, they possess a single-stranded positive RNA of about 7.7 kilobase pairs (kbp) in size (Radfor et al. Proc. 1st Int. Symp. Caliciviruses ESVV 1997. 93-99).
Like many RNA viruses, a large heterogeneity exists within the viral population of FCV. The antigenic variations, demonstrated since the beginning of the 70s by cross-serum neutralization experiments, make it possible to classify the FCVs into several viral strains or quasispecies (Radford et al. Proc. 1st Int. Symp. Caliciviruses ESVV 1997. 93-99).
Several FCV strains have been identified and isolated, in particular strain F9 (deposited with the American Type Culture Collection or ATCC under the accession number VR-782), strain 2280 (ATCC VR-2057), strain KCD (ATCC VR-651) and strain CFI (ATCC VR-654).
Vaccination against FCV was introduced since the end of the 70s from attenuated FCV strains, mainly strain F9 isolated in the USA in 1958 by Bittle (Bittle et al. Am. J. Vet. Res. 1960. 21. 547-550) or strains derived from F9 by passage in vitro or in vivo (xe2x80x9cF9-likexe2x80x9d).
Inactivated vaccines are also available. They mainly use strains 255 and 2280, which were isolated in the USA respectively in 1970 in a cat with a pneumonia (Kahn and Gillepsie. Cornell Vet. 1970. 60. 669-683; Powvey et al. J. Am. Vet. Med. Assoc. 1980. 177. 347-350) and in 1983 in a cat suffering from lameness (Pedersen et al. Fel. Prac. 1983. 13. 26-35; Pedersen N. C. and Hawkins K. F. Vet Microbiol. 1995. 47. 141-156).
Because of antigenic drift over time, antisera produced against vaccine strains isolated in the 60-70s, such as strains F9, 255 or 2280, neutralize only few isolates of the 90s. For example, the anti-F9 serum neutralizes 43% of the American isolates of the period 1990-1996, against 56% for the period 1980-89 and 86% for the period 1958-79, and only 10% of the English isolates of the period 1990-96 (Lauritzen et al. Vet. Microbiol. 1997. 56. 55-63). Accordingly, attenuated and inactivated vaccines from old FCV strains at present no longer offer sufficient protection against recent FCV strains.
The objective of the present invention is the detection of new FCV strains, which induce in cats antibodies having a broad cross-neutralization spectrum.
Another objective of the invention is the production of immunogenic preparations and of vaccines against feline calicivirosis from these FCV strains.
Yet another objective of the invention is the production of multivalent immunogenic preparations and of multivalent vaccines against feline calicivirosis and against at least one other feline pathogen.